Assisted hatching of embryos at the cleavage stage (d3) followed by embryo transfer at the blastocyst stage (d5)

Abstract

There has been some controversy surrounding the value of assisted hatching at the cleavage stage of embryo development. Many clinics hatch embryos on day 2 or 3 of culture and transfer on the same day. Studies have shown there may be an advantage for some patients to extend the culture of these embryos to the blastocyst stage. This study compares the pregnancy and implantation rates of patients who had assisted hatching on day 3 followed by day 5 embryo transfer with a similar group of patients who had blastocyst transfer without assisted hatching. A retrospective study comparing the outcome of blastocyst transfers with or without assisted hatching on day 3. All cycles were carried out at The Portland Center for Reproductive Medicine between 2001–2004. The data consisted of 22 patients who had assisted hatching at the cleavage stage of development followed by blastocyst transfer and 43 patients who had blastocyst transfer without hatching. All patients were aged 37 or over and assisted hatching was carried out either mechanically or using acid tyrodes. Chi squared analysis was used to identify any significant differences in pregnancy rates, ongoing pregnancies and implantation rates. There was no statistically significant differences between the two groups in any of the categories tested. These included the number of positive pregnancy tests, ongoing pregnancies, number of implantation sacs per embryo transfered or the number of fetal hearts per embryo transfered. It would appear that there is no advantage to hatching embryos on day 3 and culturing them to blastocyst for patients over 37 years old. From the data it seems that this group of patients who have sufficient embryos of good enough quality to have a blastocyst transfer do not require the intervention of assisted hatching.